Magnetic separator.



PATE-NTED OCT. 9, 1905.

H. H. WAIT. MAGNETIC SEPARATOR. APPLIUATION FILED APB.24,1905.

2 SHEETS-SHEET 1,

No. 832,829. PATENT@ 00T. 9,v 19116. H., H. WAIT. MAGNETm-SEPARATUR.APPLIGATOH FILED ATR. 24,1905.

UNITED sTATns PATENT orrion i HENRY H. WAIT, OF CHICAGO, lLiilNOI-S,ASSIGNOR TO INTERNATIONAL SEPARATOR COMPANY, OFCHIOAGQ ILLlNOIS, ACORPORATlON OF NEW JERSEY.

MAGNETIC SEPARATOR. 'l

Specification of Letters Patent. i'

Patented Oct. 9,1906.

Application iiled April 24.1905. Serial No. 257,047-

Toalll whom, zt may con/cern: Be it known that I, HENRY H. WAIT, acitizen of the United States, residing at Chicago, inthe county of Cookand Stateof Illinois, have invented a certain new and usefulInilprovemcnt in Magnetic Separatore, of which the following is a hill,clear, concise, and exact description. i My invention relates toi amagnetic separa- Io tor; and its object is to improve the design of' themagnetic parts so as to secure the most effective separation ofmaterials of very low permeability with a minimum expenditure of energy.

I 5 More particularly, my invention contemplates an improved form anddisposition of the magnet pole-pieces and improved forms and proportionsof the armature-teeth, such as to secure the inost eective magnetic atzetraction of the ore particles'of any given size.

In other words, one feature of the invention looks towardthedetermination of definite relations between the size of the particlesto be attracted and the size and shape of the z 5 magnetic teeth tosecure thebest results.

V I will describe my invention by reference to the accompanyingdrawings, in which- Figure .l is a sectional elevation of an oreseparator embodying said invention. Fig. 2

3ois a detail cross-section oi' the portion of the armature-surface,`showing the manner in which it is built up. Fig. 3 is a detail view ofa portion ofthe armature looking at the sides of the teeth. Figs. 4 and5 are side views of 3 5 teeth of other forms. Fig.' 6 is a diagramillustrating the influence whichthe shape oia magnetic projection ortooth has upon the attractive force exerted upon an ore particle incontact therewith. Figs. 7 and 8 are dia 4o grams illustrating theinfluence which the shape and size of the end et the tooth has upon anore particle of given size, Fig. 7 indicating the tooth too sharp iorthe .ore particle v and Fig. 8 the tooth too blunt for the ore particleof the relative size indicated. Fig. 9

lis a diagram of curves indicating the varying force of magneticattraction produced upon an ore particle of given size by teeth, theends of which have dii'lerent radii of curvature.

The same letters of reference are used to designate the same partswherever theyv are shown.

In Fig. 1 I have illustrated an ore-se aratiiig machine ofthe generaltype in wliich a der.

cylindrical armature having teeth upon its periphery is arranged torotate upon a horizontal axis between two magnet-poles of oppositepolarity facing opposite sides oi said armature. The machine is providedwith the usual feeding mechanism for passing inaterial to be separatedonto the upper surface of the cylinder, whiclriii its rotation carriesthe material through the ,air-gap between said cylinder and one of themagnet-poles S..

The machine* is provided witlrniagnetizingcoils'a c, through which acurrent is passed sufficient to setup an intei'ise magnetic flux passingfrom one magnet-pole to the other through the cylinder@ The air-gapbetween the cylinder 'and' the nnignet-pole S is the working-air-gap,through which the ore to be .separated is passed, while the magnet-poleN tliepole-piece N and the armature maybe of less length than theworking air-gap in order to economize niagnetining force. This area isalso greater than that of the working pole for the sainevreason'. Thisarea cannot be indefinitely increased, however; but the areas of the twoopposing pole-pieces should be so adjusted with reference to theair-gaps that the pull oi' the pole N plus the working strain on theshaft will approximately balance the p ull of the working pole S.

Referring to Fig. 1, it will be seen that the mixture of materialpassinvibetw'een the surface of the cylinder and the inagnet-pole S willbe .subjected to an intense magnetizing force tending to pull over themore peime* able particles toward the surface of the cylin- The cylinderis provided with teeth or permeable projections upon its periphery forthe purpose of securing convergences .of the lines of oice toward thecylind er, so that the forceoi attraction, which'is generally alongconverging lines of force, will be toward the 'cylinder rather thantoward the stationary oleepiece". The non-magnetic material, be-

ing unaffected, will fall straight down over the edge of the'ylinder,while the magnetic material will ten to follow the cylinder in its IOO irotation through a short arc below' the ,horithrough the same, which isuseful zontal plane through the axis. In the case of ores of very lowmagnetic permeahilitv the magnetic field., however strong, will only besufficient to hold the attracted material to the armature througha veryshort are below the horizontal plane, because as the 4material iscarried around in the path determined by' the rotation of the armaturethe force of attraction will act against a constantly-in creasingcomponent otgravity andV in a rapidly-decreasing magnetic field, Adividerplate b is therefore placed inposition so that its edge will beclose to the under side of thev cylinder and referably just insidel avertical tangent Vto t e cylinder. The divider, in other words, is soplaced that the magnetic material will be carried beyond its edge, whilethe non'-1nagnetic material will fall outside.

While the separating-cylinder is of considerable diameter, as shown',the niaenetic flux iior separation, must for the foregoimr reasons beconcentrated as much as possihle along a short arc'just below thehorizontal plane through the axis of the cylinder; but the frame. of themachine constituting the magnetic circuit should be of largecross-section in order to present the minimum reluctance to the magneticflux, and so to require the minimum expenditureof'energy formagnetization. For

' the foregoing reasons l therefore cut awaitr the pole-piece S sharplyjust above the hor1- y as shown in the drawings.

" which are concerned With'the size, shape, ad

Corning 4now-to the features of invention proportions ofthe magneticteeth by which the most effective attraction is secured, reference willbe had to the diagrams Figs. 6, 7, and 8. The attractive forcel exertedupon an ore particle of's-light susceptibility is dependent upon threefactors: its magnetic susce tibility, the total magnetic flux through te particle, and the anglesof convergence of the ines of force threadingthrough the particlefi. e., the rate of change in'densitv of the-fieldoccupied by the particle. Fig. 6 illustrates a spherical ore particle din position to be attracted by a sharp-pointed magnetic tooth e,

and also shows in dotted lines the manner in ceases i' tooth'gives thehost results may hebriely given as follows.: In magnetic separators oilthe type under 'consideration the density'oi the magnetic flux throughthe teeth at the working gap is verv hi h, the teeth being Eracticallsaturated. hor'such very stron elds the ine of maximum attractingstrengt of the field lies not at the extremepoint et point. In general,the outline of the and oil,

the'tooth should conform approximately in shape to the imaginaryeuipotential surface lying back ofthe rea surface of the tooth.v It willbe evident from the foregoin however, that the size and shape of thetoot should be proportioned to the size o'theore particle to beattracted, and that in general or small particles the tooth should besharper than for large particles. in Fig. 7

an ore particle is indicated in position to be attracted by acomparatively sharp tooth. By reference to this diagram it wiil he ssenthat the lines of force threading the particle diverge widely,'which initselt'is desirableA but 'which in this case is accompanied oy adecrease in the total ilux through. the parti-f cle, so that themaiiimum attractive'ores is the tooth,l but some distancebaclr, and thenot obtained. The o posits condition is in V dicated in Fig. 8, whic iillustrates an oreparL ticlerof the same size as that cig-Figs. 6 and 7in contact with avery large blunt tooth,

this case thetotal 'Hux through thev article is great; but theconvergence of the infra oi* force is.so slight that the' actualattractive force tending to pull ,the particle toward the tooth iscomparatively slight. lt is evident.

that between the small sha1 tooth indicated in Fie'. 7 and the verylarge lunt'tooth indicated by Fig. 8 there may be determinedthe size andshape of toothwhich when magneticallysaturated will exert the maximumate tract-ive force -upon the ore particle of given size.

In Fig; 9 are shown two ticle of unit size yby conical magnetic teethhaving rounded blunt ends ofvarying one vatures. j In this diagram thevertiealdis tanceindicates the relative strength of the y magnet-poletips in units of theradius of the particle which is attracted. The luxdensityv at'the surface of 'the pole-tip vis-the same' throughout. Thecurve Z in icates ro l curves which mell- A cate the attractive forcesexerted apenaparsuits with hematite ore, which is of low magneticsusceptibility, and the curve m indi- ,c'at-es they results withmagnetite, a highly- {niagnetic ore. result of actual tests.

These curves represent the It Will be seen that in e'ach case themaximum attractive effect is f produced When the rad1us of curvature ofthe ically.

dent that the constructor can at once determagnet-pole tip isapproximately two and one-half times-the radius of the ore particle.

The same rule can. be worked out mathemat- By applying this rule it willbe evi- "mine the best size and shape of teeth to be conditions areobtained with a conical tooth having a smooth rounded end, theseconditions are approximated .by the use. of teeth having generallyyramidal or conical sha e with blunted ends slighty larger than tileparticle to be attracted. t may not be practicable mechanically to formthe teeth in the ideal shape; but in Figs. 2 to 5, inclusive; I haveindicated some forms which maybe convenient in practice.

It is practically necessary that the armature or separating cylindershould be transversely laminated in structure in order that it may beturned easilyin the intense magnetic field, and to avoid the heatingeffects of eddy-currents, and such a laminated construction lends itselfreadily to -the formation of a toothed attracting-surface such asvcontemplated by this invention.

In Figs. 2 to 5,1 have illustrated the surface built up of magnetizableplates having toothed edges, vthe teeth of adjacent plates being ofprogressively different heights, so that` projections of generallypyramidal shape are thus built up. In the specific form shown in Figs. 2and 3 4the teeth of one set of disks are quite vlong with rounded lends, While the teeth of adjacent disks are cut oil more and more attheir ends, though coinciding in outline and position of their bases. Inthe form shown in Fig. 4 the teeth of adjacent disks have their ed escut at progressively different angles. n the form shown in Fig. 5 theteeth of adjac nt disks going to build up the projections areprogressively larger or smaller, but having their edges out atsubstantially the s 1e angles. It will be seen that in this constructionthe main projections built n/p by the teeth of a number of adjacentdisks Will serve to attract large particles of ore, While very smallparticles which may be in the mixture will bev caught by the smallerteeth of individual disks.

Having thus described my invention, I claim- 1L In a magnetic separator,an clement having a magnetic attracting-surface provided with a num-erof approximately pyramidal rejections each composed of a plu- 'l'alitoi) teeth of progressively different 2. A se arator-cylinder having itssurface formed o transversely-disposed magnetizable plates having teethupon their edges, the teeth of adjacent plates being of progressivelydifferent heights to form approximately pyramidal projections upon thesurface of the cylinder, the points of said projections being blunted,substantially as described.

3. In a magnetic separator, an'element having a magneticattracting-surface provided with a number of projections each composedof a plurality of teethof progressively different heights, the pointsof" said pro-` jections being blunted, and means for magnetizingsaidteeth to saturation.

In witness whereof Ihereunto subscribe my name this 17th day of April,A. D. 1905.

HENRY H. WAIT.

Witnesses:

DE Wrrr C. TANNER, IRVING MACDONALD.

